Diaphragm and process of making same



W. FRICK.

DIAPHRAGM AND PROCESS OF MAKING SAME. APPLICATION FILED 00130. 1919.

1,355,552. Patented Oct. 12, 1920.

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N 3 Am 10 1a 1a UNITED STATES PATENT OFFICE WILLIAM ERICK, OF NEW YORK,N. Y., ASSIGNOR TO CLIFF MANUFACTURHQ'G- WORKS INC., 01 NEW YORK, N. Y.,A CORPORATION OF NEW YORK.

DIAPHRAGM AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented Oct. 12, 1920.

T 0 all whom it may concern:

Be it known that I, VVILLIAM FRICK, a citizen of the United States, andresident of the city of New York, in the county of Queens and State ofNew York, have invented certain new and useful Improvements n Diaphragmsand Processes of Making the Same, of which the following is aspecification.

This invention relates 'to diaphragms for sound recording, reproducingand transmltting instruments, and particularly to diaphragms composed ofdiflerent materials and to the process of preparing the same.

It is the object of this invention to provide a diaphragm which issensitive enough to follow the higher frequencies of overtones withutmost accuracy, without producing any vibrations of its own, nottransmitted thereto by the stylus lever.

It is also an object of this invention to provide a diaphragm which is acompact unit, simple in construction and which remains unaffected byatmospheric influences.

It is another object of this invention to provide a diaphragm whoseannular sections are as nearly as possible of the same fiexuralresistance.

With these objects in view the invention consists in certain novelcombinations of parts and substances hereinafter described andparticularly pointed out in the claims.

In the accompanying drawings which are made a part of thesespecifications, Figure I is an'enlarged vertical section through areproducer provided with my 1mproved diaphragm, taken on the line A-A ofFig. H.

Fig. 11 is a plan view of a reproducer, includinga diaphragm embodyingthe invention.

Similar characters of reference indicate corresponding parts throughoutthe various views.

The diaphragm mounting shown in the accompanying drawings is the subjectmatter of a separate .and copending application for Letters Patent, inwhich I have pointed out that by numerous experiments with diaphragms ofvarious forms and materials I have evolved the theory that a diaphragmfor phonographs should be held at its rim and to the stylus-lever asrigid as mechanical means can make this possible. A dia phragm ofuniform thickness deflects considerably more in its central portion thanat its rim, and impulses of quick succession originating at the centerwill spread as waves toward the rim, and being of a different frequencyfrom the main sound wave, they will impair the correct reproduction ofthe latter. Reinforcing plates in the central part of a thin diaphragmleave an annular ring near the rim of the diaphragm which is practicallyits only deflecting part and they do not permit the whole diaphragm totake a uniform part in the sound repro-' duction. Furthermore this ringis generally subject to atmospheric influences which impair thesound-reproducing qualities of the diaphragm.

I have therefore constructed my diaphragm to be practically of uniformresistance to fiexure at all of its annular sections and use acombination of materials, best suited for this purpose on account oftheir flexural and sound transmitting qualities, and specially preparedto remain unaffected by atmospheric conditions.

With these ideas in view I have constructed my diaphragm 1 as follows: 1is a disk having the shape of a very fiat cone, or double cone, made offibrous material, as thin paper, (matrix paper) pressed into shape underapplication of heat, or of pasteboard, but preferably of soft wood,which 1 found to have the best sound producing qualities. This disk isof such size that its outer diameter is equal to that of the opening 3of the reproducer holding ring 8, and is made as thin as possible atitscircumference, to form a knife edge. At its axis, which is occupiedby the stylus-lever-screw 1 the disk is of considerable thickness andaffords thereby a long grip for this screw. This disk 1 is immersed intoa solution of glue, preferably fish glue or liquid cement, containingabout forty per cent. of formalin and when a sufiicient quantity of thissolution is absorbed by the disk, it is interposed between two sheets ofthin leather, l and 1 of larger diameter than the disk 1 and the samesolution of cement is used to join the two sheets of leather on theirborder, where they bear against each other and are held by the ledge 2and ring 3 of the reproducer casing. The diaphragm so made, is thenpressed in a suitable mold to the desired shape until the cement hasset, both outer faces of the diaphragm on 1 and 1 are then treated witha varnish solution of shellac in alcoholor a bakelite varnish and thendried.

In this manner a very light diaphragm is produced, the annular sectionsof which are of practically uniform resistance to fiexure.

The special cement permeates the fibrous material as well as theleather, filling the is provided as a further protection for the leathercoverings against atmospheric influences.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A diaphragm for phonographs and the like whose unsupported part formsa triangle in radial section, consisting of a core of fibrous materialtreated in its outer fibers with a hardening substance, and covered onboth faces with a layer of flexible material adhering to said core.

2. A diaphragm for phonographs and the like consisting of a core offibrous material forming a disk of substantial thickness at its centerand gradually sloping to a knife edge at its circumference and anairproof sheeting covering both faces of said disk.

3. A diaphragm for phonographs and the like consisting of a core ofporous material of conical-shape, a waterproof cement filling faces ofsaid core, rigidly held thereon, andv a waterproof coating covering saidsheet material on either side.

4. The method of preparing a diaphragm for phonographs or the like whichconsists in treating a disk of fibrous texture with a waterproof cementuntil a portion of said cement is absorbed by said disk, covering bothfaces of said disk with sheets of waterproofed fibrousmaterial andallowing the whole diaphragm to harden under pressure.

5. The method of preparing a diaphragm for phonographs and the like,which consists of compressing a stack of thin paper into a disk underapplication of heat, immersing said disk into a cement, comtainingformalin until a portion of said cement is absorbed by said disk;covering both faces of said disk with sheets of fibrous texture adheringto said disk and allowing the whole diaphragm to harden under pressure.

6. The method of preparing a diaphragm for phonographs and the like,which con-- sists in treating a disk of fibrous texture with a cementuntil a portion of said cement is absorbed by said disk, covering bothfaces of said disk with sheets of fibrous texture, allowing said cementto setunder pressure and applying a coating of waterproofing varnish tothe faces ofsaid diaphragm.

WILLIAM FRICK'.

